This invention relates generally to video graphics processing and more particularly to video graphics processing involving the determination of lighting effects for geometric primitives.
As is known, a conventional computing system includes a central processing unit, a chip set, system memory, a video graphics circuit, and a display. The video graphics circuit includes a raster engine and a frame buffer. The system memory includes geometric software and texture maps for processing video graphics data. The display may be a CRT display, LCD display or any other type of display.
To process video graphics data, the central processing unit executes geometric software to produce geometric primitives, which are often triangles. A plurality of triangles is used to generate an object for display. Each triangle is defined by a set of vertices, where each vertex is described by a set of attributes. The attributes for each vertex can include spatial coordinates, texture coordinates, color data, specular color data, etc. Upon receiving a geometric primitive, the raster engine of the video graphics circuit generates pixel data based on the attributes for one or more of the vertices of the primitive. The generation of pixel data may include texture mapping operations performed based on stored textures and texture coordinate data for each of the vertices of the primitive. The pixel data generated is blended with the current contents of the frame buffer such that the contribution of the primitive being rendered is included in the display frame. Once the raster engine has generated pixel data for an entire frame, or field, the pixel data is retrieved from the frame buffer and provided to the display.
Performing all of the primitive processing operations in software consumes a large amount of processing bandwidth that can limit the overall processing speed of the computing system in which the graphics processing is occurring. As graphics processing complexity increases, these limitations become more apparent.
Therefore, a need exists for a method and apparatus that provides parallel processing of graphics primitives with limited memory requirements such that a hardware geometry engine may be practically implemented.